U.S. patent application number 14/387273 was filed with the patent office on 2015-03-26 for interference coordination by means of directional antenna beams in a wireless system.
This patent application is currently assigned to Nokia Solutions and Networks Oy. The applicant listed for this patent is Klaus Ingemann Pedersen, Beatriz Soret, Jens Steiner. Invention is credited to Klaus Ingemann Pedersen, Beatriz Soret, Jens Steiner.
Application Number | 20150085771 14/387273 |
Document ID | / |
Family ID | 45894469 |
Filed Date | 2015-03-26 |
United States Patent
Application |
20150085771 |
Kind Code |
A1 |
Pedersen; Klaus Ingemann ;
et al. |
March 26, 2015 |
Interference Coordination by Means of Directional Antenna Beams in
a Wireless System
Abstract
The disclosure relate to interference coordination in wireless
communications. A first level station can obtain information for
interference coordination with a second level station to protect
the second level station from interference in arrangement where the
second level station provides a smaller coverage area than the
first level station and is at least partially located in the area
of the first level station. Use of directional antenna beams by the
first level station and/or communications by the second level
station can then be controlled accordingly.
Inventors: |
Pedersen; Klaus Ingemann;
(Aalborg, DK) ; Soret; Beatriz; (Aalborg, DK)
; Steiner; Jens; (Klarup, DK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Pedersen; Klaus Ingemann
Soret; Beatriz
Steiner; Jens |
Aalborg
Aalborg
Klarup |
|
DK
DK
DK |
|
|
Assignee: |
Nokia Solutions and Networks
Oy
Espoo
FI
|
Family ID: |
45894469 |
Appl. No.: |
14/387273 |
Filed: |
March 23, 2012 |
PCT Filed: |
March 23, 2012 |
PCT NO: |
PCT/EP2012/055236 |
371 Date: |
September 23, 2014 |
Current U.S.
Class: |
370/329 |
Current CPC
Class: |
H04W 72/0426 20130101;
H04W 84/045 20130101; H04W 16/28 20130101; H04W 72/082 20130101;
H04W 72/046 20130101; H04W 24/02 20130101; H04W 88/08 20130101 |
Class at
Publication: |
370/329 |
International
Class: |
H04W 16/28 20060101
H04W016/28; H04W 88/08 20060101 H04W088/08; H04W 24/02 20060101
H04W024/02 |
Claims
1. A method for interference coordination in wireless
communications, comprising: obtaining information by a first level
station for interference coordination with a second level station
to protect the second level station from interference by the first
level station, the second level station providing a smaller
coverage area than the first level station and being at least
partially located in the area of the first level station, and
controlling use of directional antenna beams by the first level
station according to the information.
2. A method according to claim 1, wherein the obtaining comprises
at least one of receiving information from the second level
station, using of a network listen mode, and monitoring common
reference signals by the second level station.
3. A method for interference coordination in wireless
communications, comprising: sending and/or receiving information by
a second level station for interference coordination by means of
directional antenna beams by a first level station, the second
level station providing a smaller coverage area than the first
level station and being at least partially located in the area of
the first level station, the information regarding interference by
the first level station in the area of the second level station,
and controlling communication by the second level station according
to the information.
4. A method according to claim 3, comprising signalling the
information on an interface between the first and second level
stations.
5. A method according to claim 4, wherein the interface comprises
an X2 interface or an interface provided via a network system.
6. A method according to claim 1, comprising use of an active
antenna system in the first level station.
7. A method according to claim 1, wherein the control of
directional antenna beams comprises control of joint elevation and
azimuth beamforming.
8. A method according to claim 1, comprising extending the range of
the second level station by means of the interference
coordination.
9. A method according to claim 1, wherein the interference
coordination comprises avoiding pointing beams into the area of the
second level station on resources defined in time and/or frequency
domain.
10. A method according to claim 1, wherein the information for
interference coordination comprises at least one of information of
the spatial area to be protected from interference, identity of a
second level station to be protected from interference, information
of resources desired to be protected from interference, information
of resources that are protected, and information of level of
protection desired by the second level station.
11. A method according to claim 1, wherein the first level station
comprises a macro level enhanced Node B and the second level
station comprises a pica level, a micro level or a femto level
node.
12. An apparatus for a first level station in a wireless system
where at least a second level station is provided, the second level
station providing a smaller coverage area than the first level
station and being at least partially located in the area of the
first level station, the apparatus comprising at least one
processor, and at least one memory including computer program code,
wherein the at least one memory and the computer program code are
configured, with the at least one processor, to obtain information
by the first level station for interference coordination with the
second level station to protect the second level station from
interference by the first level station, and control use of
directional antenna beams by the first level station according to
the information.
13. An apparatus according to claim 12, configured to obtain the
information from the second level station, by means of a network
listen mode, and/or by monitoring common reference signals.
14. An apparatus for a second level station in a wireless system
where at least a first level station is provided, the second level
station providing a smaller coverage area than the first level
station and being at least partially located in the area of the
first level station, the apparatus comprising at least one
processor, and at least one memory including computer program code,
wherein the at least one memory and the computer program code are
configured, with the at least one processor, to cause sending
and/or receiving of information by the second level station for
interference coordination by means of directional antenna beams by
first level station, the information regarding interference by the
first level station in the area of the second level station, and
control communication by the second level station according to the
information.
15. An apparatus according to claim 13, configured for signalling
of the information on an interface between the first and second
level stations.
16. An apparatus according to claim 13, wherein the first level
station comprises an active antenna system.
17. An apparatus according to claim 13, wherein control of
directional antenna beams is based on joint elevation and azimuth
beamforming.
18. An apparatus according to claim 13, wherein the information for
interference coordination comprises at least one information of the
spatial area to be protected from interference, identity of a
second level station to be protected from interference, information
of resources desired to be protected from interference, information
of resources that are protected, and information of level of
protection desired by the second level station.
19. An enhanced Node B comprising the apparatus according to claim
13.
20. An enhanced Node B according to claim 19, comprising a macro
node, a micro node, a femto node or a pico node.
21. A computer program comprising code means adapted to perform the
steps of claim 1 when the program is run on a processor.
Description
[0001] This disclosure e application relates to wireless
communications and more particularly to interference coordination
in a wireless communication system.
[0002] A communication system can be seen as a facility that
enables communication sessions between two or more nodes such as
fixed or mobile communication devices, access points such as base
stations, servers and so on. A communication system and compatible
communicating devices typically operate in accordance with a given
standard or specification which sets out what the various entities
associated with the system are permitted to do and how that should
be achieved. For example, the standards, specifications and related
protocols can define the manner how and what communication devices
shall communicate with the access points, how various aspects of
the communications shall be implemented and how the devices shall
be configured.
[0003] Signals can be carried on wired or wireless carriers.
Examples of wireless systems include public land mobile networks
(PLMN) such as cellular networks, satellite based communication
systems and different wireless local networks, for example wireless
local area networks (WLAN). Wireless systems can be divided into
coverage areas referred to as cells. Different types of cells can
provide different features. For example, cells can have different
shapes, sizes, power levels and other characteristics.
[0004] A user can access the communication system by means of an
appropriate communication device. A communication device of a user
is often referred to as user equipment (UE) or terminal. A
communication device is provided with an appropriate signal
receiving and transmitting arrangement for enabling communications
with other parties. Wireless systems enable mobility for users
where a mobile device can communicate over an air interface with
another communication device such as e.g. a base station and/or
other user equipment.
[0005] Examples of mobile communication systems are those based on
standards by the 3rd Generation Partnership Project (3GPP). A
recent 3GPP development is often referred to as the long-term
evolution (LTE) of the Universal Mobile Telecommunications System
(UMTS) radio-access technology. The various development stages of
the 3GPP LTE specifications are referred to as releases. In LTE
base stations are commonly referred to as enhanced NodeBs (eNB). In
LTE a node providing a relatively wide coverage area in public
landline mobile network (PLMN) level is often referred to as a
macro eNode B. Network nodes can also provide smaller service
areas. Examples of such smaller or local radio service area network
nodes include femto nodes such as Home eNBs (HeNB), pico nodes such
as pico eNodeBs (pico-eNB), micro nodes and remote radio heads. A
smaller radio service area can be located wholly or partially
within one or more larger radio service areas. In some instances a
combination of wide area network nodes and small area network nodes
can be deployed using the same frequency carriers (e.g. co-channel
deployment). Different radio technologies may be used at the same
time in a multi-layered system. Multi-layered systems are often
referred to as heterogeneous networks or HetNets. An example of a
multi-layered system is a mixture of macro base stations and small
power base stations (e.g. pico and/or micro stations). The various
layers can be deployed as part of a cellular network. It is noted
that a multi-layer LTE network is used herein only as an example
and that other solutions are also possible.
[0006] Interference caused by the different stations affects
performance. To address this coordination of interference between
different radio service areas can be provided. A way to mitigate
interference is to transmit at least some of the transmission
elements with reduced or minimal energy so that reduced power
and/or other interfering activity is caused by the transmission
thereof. Macro to pico node interference can be addressed by
resource partitioning between the macro and pico nodes such that
some transmission resources for pico are free of macro cell
interference. As an example, 3GPP Release includes so-called
enhanced inter-cell interference coordination (eICIC) feature,
where resource partitioning is implemented in the time-domain. The
basic eICIC principle relies on reserving some transmission
resources exclusively for pico by muting the macro. Thus, a
so-called muting pattern is configured to provide time periods
where one or more cells will not transmit, or the transmissions are
kept in their minimum so as to ensure interference free periods for
transmissions in one or more other cells. An example of muted
subframes is an almost blank subframe (ABS). Similarly, resource
partitioning between macro and pico nodes can also be implemented
in the frequency domain by having some frequency resources used
exclusive for pico (i.e. not subject to macro cell
interference).
[0007] Although several techniques for interference mitigation
based on multicell coordination have been proposed there may still
be occasions where other solutions might be desired, in particular
in addressing interference by macro nodes to smaller nodes. For
example, a result of resource partitioning schemes is a reduced
availability of transmission resources at the macro layer as it is
not able to use the resources reserved exclusively for pico
usage.
[0008] It is noted that the above discussed issues are not limited
to any particular communication environment and station apparatus
but may occur in any appropriate system where cells are selected by
mobile devices.
[0009] Embodiments of the invention aim to address one or several
of the above issues.
[0010] In accordance with an embodiment there is provided a method
for interference coordination in wireless communications,
comprising obtaining information by a first level station for
interference coordination with a second level station to protect
the second level station from interference by the first level
station, the second level station providing a smaller coverage area
than the first level station and being at least partially located
in the area of the first level station, and controlling use of
directional antenna beams by the first level station according to
the information.
[0011] In accordance with an embodiment there is provided an
apparatus for a first level station in a wireless system where at
least a second level station is provided, the second level station
providing a smaller coverage area than the first level station and
being at least partially located in the area of the first level
station, the apparatus comprising at least one processor, and at
least one memory including computer program code, wherein the at
least one memory and the computer program code are configured, with
the at least one processor, to obtain information by the first
level station for interference coordination with the second level
station to protect the second level station from interference by
the first level station, and to control use of directional antenna
beams by the first level station according to the information.
[0012] In accordance with an embodiment the information can be
obtained by means of at least one of receiving information from the
second level station, using of a network listen mode, and
monitoring common reference signals by the second level
station.
[0013] In accordance with another embodiment there is provided a
method for interference coordination in wireless communications,
comprising sending and/or receiving information by a second level
station for interference coordination by means of directional
antenna beams by a first level station, the second level station
providing a smaller coverage area than the first level station and
being at least partially located in the area of the first level
station, the information regarding interference by the first level
station in the area of the second level station, and controlling
communication by the second level station according to the
information.
[0014] In accordance with an embodiment there is provided an
apparatus for a second level station in a wireless system where at
least a first level station is provided, the second level station
providing a smaller coverage area than the first level station and
being at least partially located in the area of the first level
station, the apparatus comprising at least one processor, and at
least one memory including computer program code, wherein the at
least one memory and the computer program code are configured, with
the at least one processor, to cause sending and/or receiving of
information by the second level station for interference
coordination by means of directional antenna beams by first level
station, the information regarding interference by the first level
station in the area of the second level station, and control
communication by the second level station according to the
information.
[0015] In accordance with a more detailed embodiment the
information is signalled on an interface between the first and
second level stations. The interface may comprise an X2 interface
or an interface provided via a network system.
[0016] An active antenna system may be used by the first level
station for providing the directional antenna beams. Control of
directional antenna beams may comprise control of joint elevation
and azimuth beamforming. Range of the second level station may be
extended by means of the interference coordination.
[0017] The interference coordination can aim to avoid pointing
antenna beams into the area of the second level station on
resources defined in time and/or frequency domain.
[0018] The information for interference coordination may comprises
at least one of information of the spatial area to be protected
from interference, identity of a second level station to be
protected from interference, information of resources desired to be
protected from interference, information of resources that are
protected, and information of level of protection desired by the
second level station.
[0019] The first level station may comprise a macro level enhanced
Node B and the second level station comprises a pico level, a micro
level or a femto level node.
[0020] A computer program comprising program code means adapted to
perform the herein described methods may also be provided. In
accordance with further embodiments apparatus and/or computer
program product that can be embodied on a computer readable medium
for providing at least one of the above methods is provided.
[0021] It should be appreciated that any feature of any aspect may
be combined with any other feature of any other aspect.
[0022] Embodiments will now be described in further detail, by way
of example only, with reference to the following examples and
accompanying drawings, in which:
[0023] FIG. 1 shows a schematic diagram of a communication system
where the invention may be embodied;
[0024] FIG. 2 shows a schematic diagram of a control apparatus
according to some embodiments;
[0025] FIGS. 3 and 4 show flowcharts according to certain
embodiments; and
[0026] FIG. 5 shows an example of embodiment employing elevation
and azimuth beamforming.
[0027] In the following certain exemplifying embodiments are
explained with reference to a wireless or mobile communication
system serving mobile communication devices. Before explaining in
detail the exemplifying embodiments, certain general principles of
wireless communications are briefly explained with reference to
FIGS. 1 and 2 to assist in understanding the technology underlying
the described examples.
[0028] A non-limiting example of the recent developments in
communication system architectures is the long-term evolution (LTE)
of the Universal Mobile Telecommunications System (UMTS)
standardized by the 3rd Generation Partnership Project (3GPP). More
recent development of the LTE, Release 10 and upwards, are
sometimes referred to as LTE-Advanced. The LTE employs a mobile
architecture known as the Evolved Universal Terrestrial Radio
Access Network (E-UTRAN). Base stations of such systems are known
as evolved or enhanced Node Bs (eNBs) and may provide E-UTRAN
features such as user plane Radio Link Control/Medium Access
Control/Physical layer protocol (RLC/MAC/PHY) and control plane
Radio Resource Control (RRC) protocol terminations towards the
communication devices. Other examples of radio access system
include those provided by base stations of systems that are based
on technologies such as wireless local area network (WLAN) and/or
WiMax (Worldwide Interoperability for Microwave Access).
[0029] Mobile communication devices 1 can be provided with wireless
access via base stations or similar wireless transmitter and/or
receiver nodes providing radio service areas or cells. The base
stations are typically connected to a wider communications network
via appropriate gateways. FIG. 1 shows two radio service areas 10
and 20. The services areas or cells are provided by respective base
station nodes 12 and 22. A mobile communication device 1 may be
located in the service areas of different cells, communicate with
more than one cell and be handed over from a cell to another. In
particular, FIG. 1 depicts heterogeneous network comprising a macro
cell 10 provided by wide area base station 12 and a smaller cell 20
provided by local base station 22. The small cell can be e.g. a
pico-cell, a micro cell or a femto cell. In accordance with
LTE-Advanced the transmission/reception points or base stations can
comprise wide area network nodes 12 such as a macro eNode B (eNB)
which may, for example, provide coverage for an entire macro cell
or similar radio service area. The small or local radio service
area network nodes may be provides for example by Home eNBs (HeNB),
pico eNodeBs (pico-eNB), or femto nodes. Some applications may
utilise radio remote heads (RRH) that are connected to for example
an eNB.
[0030] Base station nodes are connected to a core communications
network via appropriate gateways and/or backhaul systems. The
smaller area stations can be connected to the core for example by a
separate gateway/backhaul function and/or via the controllers of
the macro level station. For example, user traffic from station 22
can be backhauled to a mobile core network over an Internet
Protocol (IP) link provided e.g. by residential or office broadband
connection available locally. Base station nodes 12 and 22 may
communicate via each other via fixed line connection and/or air
interface. The logical connection 14 between the base station nodes
can be provided for example by an X2 interface.
[0031] It is noted that the number of cells and the cell borders
are only schematically shown for illustration purposes in FIG. 1,
and that these can vary considerably from that shown. It shall thus
be understood that the size and shape of the cells may vary
considerably from those shown in FIG. 1, and that in real life
scenarios there are likely to be more than two cells.
[0032] Base stations are typically controlled by at least one
appropriate controller apparatus so as to enable operation thereof
and management of mobile communication devices in communication
with the base stations. The control apparatus can be interconnected
with other control entities. FIG. 2 shows an example of a control
apparatus capable of operating in accordance with the embodiments,
for example to be coupled to and/or for controlling a base station.
The control apparatus 30 can be arranged to provide control on
communications in the service area of a cell. In some embodiments a
base station can comprise a separate control apparatus. In other
embodiments the control apparatus can be another network element.
The control apparatus 30 can be configured to provide control
functions in association with generation and communication of
information of cells and/or control functions based on such
information by means of the data processing facility in accordance
with certain embodiments described below. For this purpose the
control apparatus comprises at least one memory 31, at least one
data processing unit 32, 33 and an input/output interface 34. The
control apparatus can be coupled to a receiver and/or transmitter
of the base station via the interface. The control apparatus can be
configured to execute an appropriate software code to provide the
control functions. The control apparatus and functions may be
distributed between a plurality of control units. In some
embodiments, each base station can comprise a control apparatus. In
alternative embodiments, two or more base stations may share a
control apparatus.
[0033] A possible mobile device 1 for communications with the base
stations is often referred to as user equipment (UE) or terminal.
An appropriate mobile device may be provided by any device capable
of sending radio signals to and/or receiving radio signals from
multiple cells. Non-limiting examples include a mobile station (MS)
such as a mobile phone or what is known as a `smart phone`, a
portable computer provided with a wireless interface card or other
wireless interface facility, personal data assistant (PDA) provided
with wireless communication capabilities, or any combinations of
these or the like. A mobile device may provide, for example,
communication of data for carrying communications such as voice,
electronic mail (email), text message, multimedia and so on. Users
may thus be offered and provided numerous services via their
devices. Non-limiting examples of these services include two-way or
multi-way calls, data communication or multimedia services or
simply an access to a data communications network system, such as
the Internet. User may also be provided broadcast or multicast
data. Non-limiting examples of the content include downloads,
television and radio programs, videos, advertisements, various
alerts and other information. The mobile device may receive and
transmit signals over an air interface with multiple base stations
via an appropriate transceiver apparatus.
[0034] A wireless communication device, such as a base station
and/or a mobile station, can be provided with a Multiple
Input/Multiple Output (MIMO) antenna system for enabling multi-flow
communications. MIMO arrangements as such are known. MIMO systems
use multiple antennas at the transmitter and receiver along with
advanced digital signal processing to improve link quality and
capacity. More data can be received and/or sent where there are
more antenna elements.
[0035] Interference coordination can be provided between the
different layers in heterogeneous networks. In the herein described
embodiments features of directional antenna beams are utilised to
provide spatial resolution to protect lower level stations from
interference. In accordance with an embodiment shown by the
flowchart of FIG. 3 this can be provided by a method for
interference coordination where information is obtained at 40 by a
first level station for interference coordination with a second
level station to protect the second level station from interference
by the first level station. The second level station provides a
smaller coverage area than the first level station and is at least
partially located in the area of the first level station. Use of
directional antenna beams by the first level station can then be
controlled at 42 according to the information. The second level
station may be informed of the control so that it becomes aware of
resources where interference by the first level station is
reduced.
[0036] The information can be obtained e.g. by receiving the
information from the second level station, using a network listen
mode, and/or monitoring common reference signals by the second
level station.
[0037] The option of receiving at least a part of the information
from the second level station and/or sending information regarding
the interference coordination to the second level station is shown
in FIG. 4 where information is send and/or received by the second
level station for interference coordination by means of directional
antenna beams by a first level station at 44 and where
communications by the second level station are controlled at 46
according to the information.
[0038] In accordance with a more detailed embodiment spatial
interference coordination of antenna beams of a macro level base
station (beam steering) is used for certain time and/or frequency
resources. The spatial interference coordination may be used e.g.
for LTE co-channel deployment of macro and small cells and downlink
(DL) interference from macro to small cells. By controlling the
downlink interference to small cells, more users can be offloaded
from the macro layer, resulting in an overall network performance
gain. The spatial interference coordination is used such that use
of resources that can be used by a smaller base station to serve
its users can be provided in a range extension area denoted by 21
in FIG. 1. To provide this certain parts of macro cells can be
blanked out. More particularly, areas covered also by co-channel
smaller cells can be blanked out by means of beamforming. During
blanking out the relevant small cell may transmit whilst taking
benefit from the lowered interference levels by the macro level
station. This may be provided instead of excluding resources or
reducing the transmission power on certain resources. The blanking
out can be provided by means of inter-eNB signaling, control
procedures, and management and/or coordination of transmissions in
space domain.
[0039] FIG. 1 illustrates a simplified scenario as an example of a
multi-layer network with macro and a small cell, for example a pico
cell. It is noted that this example uses the term "pico" to denote
small cells for simplicity, and that the same principles also apply
for other cases e.g. where pico is substituted by a micro and/or
femto level cell or in a system where different levels are
employed.
[0040] Assuming an operating bandwidth of 10 MHz, a typical
configuration of the macro base station (eNB) is 46 dBm transmit
(Tx) power per sector, 14 dBi antenna gain (including feeder loss),
which results in an equivalent isotropic radiated power (EIRP) of
60 dBm. The pico eNB can have, for example, an effective isotropic
radiated power (EIRP) of 35 dBm, which results in significantly
smaller coverage than the macro eNB.
[0041] The coverage area of a pico eNB is not only limited by its
transmit power, but also to a large extent by interference
experienced from a macro eNB. Thus, if a serving cell selection is
based on downlink user equipment (UE) measurements such as
reference symbol received power (RSRP) only UEs in the close
vicinity will end up being served by the pico. The service area of
the pico can be increased by applying a so-called range extension
(RE), where a cell specific bias to the UE measurement of X dB is
applied for a pico to favour connecting to it. However, in a
traditional co-channel scenario without any explicit interference
management, it is typically only possible to use small values of
the RE, say few dBs, as pico UEs will otherwise experience too high
interference from the macro layer.
[0042] The embodiments address interference from macro level to
pico level nodes. Reduction in macro interference can be used to
allow use of higher pico RE offsets to increase the offload from
the macro-layer.
[0043] In accordance with an embodiment features of active antenna
system (AAS) system and (e)ICIC are employed. According to a
possibility shown in FIG. 5 coordinated spatial interference
management from macro eNB 50 providing cell 52 to pico eNB
providing cell 54 is used for cases where the macro eNBs are
equipped with active antenna systems (AAS) supporting joint
elevation and azimuth beamforming. The basic principle of AAS, as
illustrated in FIG. 4, it that a macro-eNB 50 is able to form
highly directional beams 56, 58 to only illuminate a relative small
confined area in its cell.
[0044] Given the assumption of macro sites with AAS, coordination
between macro and pico can be provided such that macro avoids
creating interference to the pico or other smaller station at
certain resources. This can be avoided by not pointing the beams
from the macro station 50 to the area covered by a smaller station.
The resources where the macro avoids pointing beams in the
direction of the smaller coverage area can be defined in the
time-domain and/or frequency domain and are coordinated between
macro and pico. At protected resources where no macro beam is
pointed at the smaller coverage area the smaller node can serve
users that it would otherwise not be able to serve due to too high
macro-cell interference. Nevertheless, eNB 50 can serve other
devices in the area 52 by means of the beam 58.
[0045] Relevant macro eNB(s) can be provided with knowledge of the
approximate spatial area to be protected in its coverage area. In
accordance with a possibility to get this information each macro
eNB can obtain information on the spatial location of each pico
cell by using network listen mode (NLM) and monitor the common
reference signals (CRS) transmitted from the pico. By doing this,
the macro eNB can estimate the azimuth-elevation of the pico-eNB
via simple signal processing algorithms. A possible way of getting
this information is that pico-eNB(s) provide explicit information
to the macro-eNB over an interface such as the X2. The pico node(s)
may inform the macro node which pico-UEs would benefit from being
protected from macro cell interference. If such information is
provided by the pico-eNB(s), the macro eNB can monitor the
transmitted signals from the relevant pico-UEs and estimate the
corresponding azimuth-elevation towards those.
[0046] Both of these methods can be applied simultaneously in a
system. In this case a macro-eNB can get relative accurate
estimation of the azimuth-elevation area covered by a smaller eNB.
The estimate can become rougher if only part of the information is
available.
[0047] Additional inter-eNB signaling can be introduced between
macro and smaller nodes to facilitate coordination of resources
where a certain smaller eNB is protected from interference by a
macro eNB. The signalling can be provided e.g. via X2 interface.
Inter-eNB signaling to facilitate such coordination can include
cases where e.g. a pico eBN or another smaller node recommends
certain resources to be protected from macro interference. Also,
signaling where a macro eNB simply informs e.g. a pico node on
which resource it can assume that there is reduced macro cell
interference may be provided. A smaller eNB can also signal to a
macro eNB whether it would benefit from having more resources
protected from macro interference, or whether it could tolerate
having less resources protected.
[0048] Inter-eNB signaling of "protected resources" with reduced
macro cell interference can be expressed either in the frequency
domain (e.g. as set of physical resource blocks (PRBs)), in the
time-domain (e.g. on subframe resolution as for eICIC cases), or as
a combination of time and frequency.
[0049] Inter-eNB signalling can be provided for example by
introducing new X2 messages or by introducing new information
elements (IEs) to existing messages. Instead of interface such as
X2, the spatial interference coordination can also be implemented
using information exchange via a centralized network unit such as
operation and maintenance (OAM) element.
[0050] The proposed scheme can also be combined with the existing
eICIC solution, or equivalent partial frequency domain partitioning
schemes. As a further possibility, if position information, for
example GPS information is available from the eNBs, such knowledge
may also be utilized for estimating azimuth-elevation from a macro
node in its coverage area.
[0051] Embodiments can be employed to avoid or at least reduce
interference and to allow efficient use of time and/or frequency
resources in macro and smaller eNBs. Range expansion of the small
cell area(s) can be provided. Improved system capacity may be
provided by use of adaptive antenna beam-forming to blank out
certain parts of a cell instead of muting sub-frames in order to
reduce inter-cell interference. When a macro node actively aims to
avoid generation of interference for a smaller cell at certain
resources, the smaller cell can serve users on those resources that
would otherwise not be feasible due to too high macro-cell
interference. While the macro avoids generating interference
towards a certain smaller cell, it can still serve users that are
spatially separated from that particular service area. Thus, the
macro node may be able to transmit on all of its resources all the
time.
[0052] It is noted that whilst embodiments have been described
using LTE and LTE Advanced as examples, similar principles can be
applied to any other communication system or indeed to further
developments with LTE. Thus, instead of LTE, the invention may be
applied to other cellular standards as well. Different layers may
be implemented in different radio access technology (RAT), for
example such that a GSM macro layer and LTE micro layer is
provided. Also, instead of carriers provided by base stations at
least one of the carriers may be provided by a communication device
such as mobile user equipment. For example, this may be the case in
application where no fixed equipment provided but a communication
system is provided by means of a plurality of user equipment, for
example in adhoc networks. Therefore, although certain embodiments
were described above by way of example with reference to certain
exemplifying architectures for wireless networks, technologies and
standards, embodiments may be applied to any other suitable forms
of communication systems than those illustrated and described
herein.
[0053] This above embodiment can be provided as complementary to
other interference coordination techniques, for example on those
provided based on 3GPP standards e.g. in frequency and time
domain.
[0054] The required data processing apparatus and functions of a
base station apparatus, a communication device and any other
appropriate apparatus may be provided by means of one or more data
processors. The described functions at each end may be provided by
separate processors or by an integrated processor. The data
processors may be of any type suitable to the local technical
environment, and may include one or more of general purpose
computers, special purpose computers, microprocessors, digital
signal processors (DSPs), application specific integrated circuits
(ASIC), gate level circuits and processors based on multi core
processor architecture, as non-limiting examples. The data
processing may be distributed across several data processing
modules. A data processor may be provided by means of, for example,
at least one chip. Appropriate memory capacity can also be provided
in the relevant devices. The memory or memories may be of any type
suitable to the local technical environment and may be implemented
using any suitable data storage technology, such as semiconductor
based memory devices, magnetic memory devices and systems, optical
memory devices and systems, fixed memory and removable memory.
[0055] In general, the various embodiments may be implemented in
hardware or special purpose circuits, software, logic or any
combination thereof. Some aspects of the invention may be
implemented in hardware, while other aspects may be implemented in
firmware or software which may be executed by a controller,
microprocessor or other computing device, although the invention is
not limited thereto. While various aspects of the invention may be
illustrated and described as block diagrams, flow charts, or using
some other pictorial representation, it is well understood that
these blocks, apparatus, systems, techniques or methods described
herein may be implemented in, as non-limiting examples, hardware,
software, firmware, special purpose circuits or logic, general
purpose hardware or controller or other computing devices, or some
combination thereof. The software may be stored on such physical
media as memory chips, or memory blocks implemented within the
processor, magnetic media such as hard disk or floppy disks, and
optical media such as for example DVD and the data variants
thereof, CD.
[0056] The foregoing description has provided by way of exemplary
and non-limiting examples a full and informative description of the
exemplary embodiment of this invention. However, various
modifications and adaptations may become apparent to those skilled
in the relevant arts in view of the foregoing description, when
read in conjunction with the accompanying drawings and the appended
claims. However, all such and similar modifications of the
teachings of this invention will still fall within the spirit and
scope of this invention as defined in the appended claims. Indeed
there is a further embodiment comprising a combination of one or
more of any of the other embodiments previously discussed.
* * * * *